You often see cute knot ornaments like the one in this image in Japanese gift stores. Many foreigners may think they are Japanese-style ribbons. Like ribbons, they are used for gift wrapping, but they have far more rules for usage than ribbons.
Ribbons can be easily untied. However, the more the Mizuhiki is pulled, the stronger the knot is tied. In Japan, it is said that the connection between people like this knot. Therefore, at weddings, gifts are often decorated with Mizuhiki that cannot be easily untied, which means the love between the newly-married couple will last forever. There are also rules regarding the colors used for Mizuhiki. Those used at funerals are usually black and white.
I looked up the origin of Mizuhiki. One theory is that during the Ming Dynasty in China, cargoes shipped to Japan had white and red ropes tied around the cargo boxes, and the Japanese mistakenly thought this was a custom used for gifts, and subsequently began to tie gifts out with the same type of string.
I never would have guessed that an old custom has long history started out as a misunderstanding!